Electroacoustic Transducer

a transducer and electroacoustic technology, applied in the direction of piezoelectric/electrostrictive transducers, transducer types, generators/motors, etc., can solve the problems of difficult to reduce the thickness of piezoelectric ceramic speakers, difficult to obtain high sound pressure over a wide range of frequencies, and inability to obtain low frequency sound, etc., to achieve the effect of convenient manufacturing, high sound pressure, and inexpensive electroacoustic transducers

Active Publication Date: 2008-09-11
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0023]If the flexible thin film is placed so that it covers the entire area of the frame and the entire area of one of main surfaces of each of piezoelectric elements is bonded to the flexible thin film, the flexible thin film can be bonded to the frame so that it covers the entire area of the opening of the frame and the piezoelectric elements can be easily bonded to the flexible thin film. Accordingly, the electroacoustic transducer can be more easily manufactured, and a more inexpensive electroacoustic transducer can be provided.
[0024]If the piezoelectric elements each has a substantially trapezoidal shape having an upper base and a lower base corresponding to the end portion coupled to the frame, the free end portion corresponding to the upper base can be more easily displaced. Accordingly, a higher sound pressure can be obtained.
[0025]If the length of the end portion of each of the piezoelectric elements which is coupled to the frame is smaller than a width of the opening at the gap across which the piezoelectric elements face each other (the width of the opening is a dimension in the same direction as the length direction of the end portion), the piezoelectric elements can be easily displaced on the side of the gap across which the piezoelectric elements face each other. Accordingly, a higher sound pre

Problems solved by technology

As a result, sound in a low frequency range cannot be obtained.
That is, a high sound pressure cannot be obtained over a wide range of frequencies.
This makes it diffi

Method used

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Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0075]FIGS. 1(a) and 1(b) are an elevational cross-sectional view and a plan view of an electroacoustic transducer according to the present invention, respectively. An electroacoustic transducer 1 is suitable for use as a piezoelectric speaker. The electroacoustic transducer 1 includes a frame 4 obtained by bonding a first frame member 2 and a second frame member 3 together. The frame members 2 and 3 are made of an appropriate rigid material such as metal or ceramic. In this embodiment, the frame members 2 and 3 are made of metal.

[0076]The frame 4 includes an opening 4a. In the opening 4a, a flexible thin film 5 is bonded to the frame 4 so that it covers the entire area of the opening 4a. More specifically, the peripheral portion of the flexible thin film 5 is sandwiched and fixed between the frame members 2 and 3 so that the flexible thin film 5 covers the entire area of the opening 4a.

[0077]The flexible thin film 5 is composed of a flexible thin film made of a material that is no...

second embodiment

[0092]FIG. 3 is a plan view of an electroacoustic transducer according to the present invention. In an electroacoustic transducer 21, the piezoelectric elements 6 and 7 face each other with a gap therebetween in the opening 4a of the frame 4. At the gap A, a rigid plate 22 having a rigidity higher than that of the flexible thin film 5 is bonded to the flexible thin film 5. The rigid plate 22 can be made of an appropriate material having rigidity higher than that of the flexible thin film 5. In this embodiment, the rigid plate 22 is composed of a fiber reinforced plastic plate having a thickness that is substantially the same as that of the piezoelectric elements 6 and 7. The thickness of the rigid plate 22 is not necessarily substantially the same as that of the piezoelectric elements 6 and 7. It is desirable that the rigid plate 22 be made of the lightest material with high rigidity.

[0093]The rigid plate 22 is bonded to the flexible thin film 5. Accordingly, when the piezoelectric ...

third embodiment

[0094]FIG. 4 is a plan view of an electroacoustic transducer according to the present invention. In an electroacoustic transducer 31, first to fourth piezoelectric elements 32 to 35 are provided in the opening 4a of the frame 4. More than two piezoelectric elements may be provided in the opening 4a.

[0095]Like the piezoelectric elements 6A and 7A used in the electroacoustic transducer 12, the piezoelectric elements 32 to 35 each has a substantially trapezoidal shape. Each of the piezoelectric elements 32 to 35 has an upper base at a tip portion thereof, and is fixed to the frame 4 at a lower base thereof. In this embodiment, the flexible thin film 5 is similarly fixed to the frame 4 so that it covers the entire area of the opening 4a. In a gap region A on the side of the tip portion of each of the piezoelectric elements 32 to 35 having a substantially trapezoidal shape, a rectangular rigid plate 30 is bonded to the flexible thin film 5. Accordingly, in this embodiment, using the rig...

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Abstract

An electroacoustic transducer having one end portion of a first piezoelectric element and one end portion of a second piezoelectric element fixed to a frame such that the first piezoelectric element and the second piezoelectric element are supported by the frame in an opening of the frame in the cantilever manner. A flexible thin film is bonded to the frame and the first and second piezoelectric elements so that it covers at least a gap between each of the piezoelectric elements and the frame. The other end portions of the piezoelectric elements are free end portions, and face each other with a gap therebetween.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application is a continuation of International Application No. PCT / JP2006 / 315587, filed Aug. 7, 2006, which claims priority to Japanese Patent Application No. JP2005-339033, filed Nov. 24, 2005, the entire contents of each of these applications being incorporated herein by reference in their entirety.FIELD OF THE INVENTION[0002]The present invention relates to electroacoustic transducers used as sounders such as speakers, and, more particularly, to an electroacoustic transducer having a cantilever support structure in which a piezoelectric element is supported at one end portion thereof.BACKGROUND OF THE INVENTION[0003]In recent years, electroacoustic transducers such as a speaker and a buzzer using a piezoelectric effect are widely used. For example, the following Patent Document 1 discloses a sounder 101 illustrated in an elevational cross-sectional view in FIG. 11. The sounder 101 includes a box 102. One end portion of a pi...

Claims

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Application Information

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IPC IPC(8): H04R17/00
CPCH04R17/10
Inventor KURODA, HIDEAKISONODA, YOSHIHIRO
Owner MURATA MFG CO LTD
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